Centrifuge



W. B. WESCOTT Nov. 26, 1929.

CENTRIFUGE Patented Nov. 26, 1929 UNITED STATES PATENT oFricE WILLIAMBURTON WESCOTT, OF WELLESLEY, MASSACHUSETTS, ASSIGNOR TO AMERI- CANPROTEIN CORPORATION, BOSTON, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS onn'rnrruen Original application filed December 5, 1922,Serial No. 605,090, Divided and this "application filed June 17,

The present invention relates to centrifuges and more particularly tothe type of centrifuge disclosed in my copending application Ser. No.605,090, filed December 5,1922, of

s which this application is a division. The object of thepresentinvention is to provide a centrifuge whichwill separateconstituents of a liquid mixture from one another in an economical andpractical manner. To 1o this end the invention consists in the centrifue hereinafter described and particularly de ned in the claims.

The drawing is a vertical sectional elevation of the preferred form ofthe centrifuge.

The invention is herein illustrated and described as utilized for theseparation of the constituents of animal blood which is obtained andcollected during the slaughter of animals upon the killing floor. 2vention is especially adapted for separating the red corpuscular matterfrom the plasma proteins of the blood to obtain an edible food product,as disclosed in my copending application above referred to.

The valuable and nutritious properties of the proteins occurring asconstituents of ammal blood have been recognized for some time by thosewho'have searched for new foods. The very nature of blood has preventedany extensive use of anything resemblin blood. in color and form. Notonly must the food or food bases derived from blood and the methods bywhich they are produced boot a character such as to pass rigidGovernment inspect'ion', but also for commercial reasons must theproducts be sufficiently changed in appearance as to in no way resembleIt is desirable in order that their use may exon uv tend into thevarious edible fields, that theproducts be free from the characteristicodor of meat and of infinitely better keeping qualities than ordinaryanimal blood. Very small amounts of whole blood are occasionally used inarticles of food such as blood pudding, blood sausage and blood bread,but only in foods which are subjected to very thorough sterilization bycooking before use. Up to the present time it has been impossible'tocollect animal blood and separate its constitucnt proteins for use asedible products in In particular the in-" blood.

Serial No. 37,688.

a practical commercial way. The separated constituent proteins of bloodhave not heretofore been available, therefore, as foods or food bases.

Products prepared from blood by usual methods are available only fortechnical or industrial uses and even such products are not whollysatisfactory because of poor keeping qualities, poor color, lowsolubility, strong odor,. and a marked tendency to change theircharacteristics with age. The bulk of the slaughterhouse blood producedtoday is converted into a dr product to be used as fertilizer. In'addltion to the quantity of slaughterhouse blood which is utilized forfertilizer a relatively small amount of such blood is used for theproduction of blood sera, commonly known upon the market as bloodalbumins. These products find use in the textile and leather industriesas Well as for the production of waterproof -veneers. Ac-

cording to usual methods for their production the desired quantity ofblood is collected in pails or otherwise in a'more or less carelessmanner during the slaughter of the animal andwhi'le the blood is gushingdown upon the killlng floor. The blood thus collected is permitted toclot in a large shallow vessel, the clot is thereafter out into smallcubes by means of a coarse wire net and the cubes then spread u on afine wire net todrain. The serum I yielded by the contraction of thefibrin in the small cubes is colored red by the free hemoglobinresulting from both the mechanical rupture of the corpuscles durin theseverance of the clot and also by hemolysis caused by the introductionof extraneous moistureduring the collection of the blood. The color ofsuch sera produced by this general method has been slightly improved bycol,- lecting the sera from the drainage operation in steps, the firstrunyielding a deep red product and the second run a product of a lighterred color. These products are oftentimes then passed through acentrifuge in order to clarify them, but because of the manner in.

which the blood is collected it is contaminated with bacteria such as torender the sera unfit for edible purposes and with sufficient moisturefrom the drippings from the animal to produce by hemolysis a redness inthe finalserum which is alone sufficient to prevent their use for ediblepurposes. The action of the centrifuge has no eflect upon this freehemoglobin and the red color may only be removed from such sera by aninvolved chemical process. In addition to this clotting method the bloodmay be defibrinated, as by stirring. In this process the fibrin clotsabout the stirrer and may be subsequently separated from the serum. Themechanical action of the stirrer upon the red corpuscles operates tofree considerable hemoglobin which, together with the amount ofhemoglobin freed by hemolysis due to extraneous moisture introduced intothe blood during its collection, serves to impart suflicient redness tothe resulting serum as to render it entirely unfit for edible purposes.

In addition to the foregoing, immune sera and similar products areproduced in special laboratories by taking small amounts of blood ofspecially treated animals without permanent injury to the animals. Theblood thus obtained is manipulated in small individual lots underconditions which are feasible only in special laboratories and which areentl'rely impractical from the commercial point of view of producingfood products. These sera as found upon the market usually containadditional preservatives to prevent their early decomposition, Y

According to the method disclosed in the above mentioned copendingapplication each animal after being stunned and hoisted into properposltion is cut 1n such a manner as to obtain its blood without contactwith the hide of the animal, whereby contamination due to bacterialinfection or hemolysis is eliminated. This operation is convenientlycarried out by an improved form of butchering knife of the typedisclosed in the application of F. C. Atwood, Ser. N 0. 605,091, filedDecember 5, 1922. Blood is conducted through a hollow handle of theknife into suitable cans which contain an amount of anti-coagulanttoprevent coagulation of the blood. As described in my parentapplication the cans are provided with spe cially designed covers toprevent condensation of moisture and consequent hemolysis of the blood.The blood of each animal is preferably drawn into a separate can whichmay be conveniently tagged or otherwise designated pending the finalinspection of the animal by the inspector, so that in the event that theanimal is'unfit for food usethe can of blood may be rejected withoutcontamination of the blood from other animals.

After the collection of the blood in the containers it is now incondition for further treatment for the production of edible productsfree-from the objectionable red color which has heretofore accompaniedthe production of albumins from animal blood. The separation of the redcorpuscular matter from the clear serum portion is preferablyaccomplished by the passage of the blood through a centrifuge of thecontinuous type, the preferred form of which forms the subject matter ofthe present invention.

The illustrated embodiment of the invention comprises in general anelongated bowl 30 suspended from the end of the shaft 32 adapted to bedriven in the usual manner by a turbine 33 at high speed. Theblood to beseparated is introduced directly from the containers in which it iscaught upon the killing floor through a conduit 36 and delivery nozzle38 to the interior of the bowl 230 at its lower end. The delivery nozzle38 terminates sufficiently near the lower end of the interior of thebowl 30 as to insure that the entering blood stream passes into the bowlwithout encountering any portion of the metal of the rotating bowlitself. During the centrifuging operation the red corpuscular matter isthrown to the outside, leaving the light colored solution as an annularlayer nearer the center. Both layers are withdrawn from the upper partof the bowl 30 through discharge passages 40, 42 leading into andcommunicating with discharge nozzles 44, 46 as shown. The separatedproducts are collected in rela tively large containers, not shown.

During the operation of the centrifuge, the

blood stream is delivered directly into the inthe blood stream will havetraversed up- ,wardly to somewhere near the mid portion of the bowlduring the interval that it is being brought up to speed. The interiorof the bowl 30 from the delivery nozzle to the point in the bowl 30where the blood stream attains the speed of the bowl is purposely madedevoid of all obstructions. This construction of apparatus, it will beobserved, enables. the entering blood stream tobe brought up to speedsolely by means of a liquid cushion and in this manner the smashing ofthe red corpuscles characteristic of the-elfect of known centrifuges isentirely avoided. l

. The problem of completely separating the red corpuscular matter fromthe clear liquid portion of the blood is rendered particularly difiicultbecause of the ability of a very small quantity of hemoglobin to colorsuch clear liquid portion. Inendeavoring to secure a complete separationby means of the centrifuges at present upon the market considerabledifficulty was encountered even though all of the abovementionedconditions as to the design of the lower part of thecentrifuge bowlthrough the interior of the centrifuge from around thedelivery nozzle.These air currents even though relatively small seem to have the effectof carrying a portion or mist of whole blood from the entering bloodstream upwardly through the central portion of the centrifuge where itwas mixed with the separated clear liquid portion. In addition thepassage of the air currents in this manner seemed to operate to inducemixing between the separated'portions of blood and to, in this manner,interfere with the desired complete separation. The occurrence of suchair streams may be successfully prevented indifferent ways as, forexample, by closing the openings through which such air currents wereintroduced into the bottom of the bowl around the delivery nozzle, andfor this purpose the delivery nozzle 38 and its supporting casing 50.are, in the centrifuge illustrated in the drawing, formed integrally inamanner such that the casing completely seals the space surrounding thedelivery nozzle and through which the objectionable air currents were,in

the commercial centrifuges, found to pass.

The usual practice in the construction of centrifuges of the typeillustrated in the "lrawing contemplates the provision of vanes 54.atfixed to the rotating bowl and which serve to assist in maintainingthe blood rotating at the speed of the bowl. As illustrated, the vanes54 are of gradually increasing width or depth at the lower portionthrough the provision of lower edge portions curving inwardly from ajoint adjacent the periphery of the bowl to the juncture of the vanes.This causes the upwardly moving liquid'stream to be gradually engagedand rotated by the vanes without shock or rupture of the red corpuscles.Such vanes at their tops present surfaces favorable for the conduction,by capillarity or surface tension or a similar force, of some of the redcorpuscles from the outer portions of the bowl inwardly againstcentrifugal force into the clear liquid portion which has beencompletely separated from the p red corpuscles. The effect of suchtraverse or creeping of the red corpuscles'along the sur faces at thetop of these vanes was to impart s'ufficient objectionablered'coloration to-thc effluent as to render it unfit for useas a foodbase. This objectionable feature is overcome .in the present instance bythe provision of a dam 56 comprising a tapered conical structurearranged to form a tapered passage. leading directly to the dischargeoutlets 46 through which the red corpuscular matter is withdrawn fromthe centrifuge. The in 'phate's ner portions of the dam terminate atapproximately the boundary wall between the clear liquid and the redcorpuscular matter in an opening formed by cut-away portions of thevanes themselves. In this manner a very indirect path is afforded forthe traverse of the red corpuscles fromthe upper portion of thebowl-near the discharge. outlets. The contact of the vanes with the redcorpuscular matter is at the top of the vanes limited to a point spaceda considerable distance from the boundary wall of the clear liquidportion. The portion of the dam 53 included in the opening formed by thecut-away portions of the vanes does not seem to exert sufficient actionupon the red corpuscular matter to overcome the tremendous centrifugalforce tending to throw such matter to the exterior of the bowl andtoward the discharge outlets. Any red corpuscles which actually totraverse around the end of the dam find themselves in a secondarychamber 58 immediately upon the dam, in which the centrifugal forceoperates to throw them to the outside, thus permitting the clear fluidportion to pass out through its discharge nozzle-entirely uncontaminatedby any red corpuscles. At the end of each days run the centrifuge iscleaned and whatever red corpuscular matter accumulates in the secondarychamber is removed at this time.

J The straw yellow effluent resulting from the centrifuging operation isfree from or contains so little hemoglobin as to be entirely devoid'ofany suggestion of the objectionable red color of blood.v This effluentcomprises a solution of'the plasma'proteins of the blood the blood of aseries of animals as distinguished fromthe blood of a single isolatedanimal is a very important distinction from the viewpoint ofstandardization by the baker or other person using this product or anysubsequent products derived therefrom. This lasma solution has a gravityof approximately 4 B. and contains about 9% solids, including smallamounts of'such salts as chlorides, carbonates, sulphates and phosofsodium. potassium, calcium, magnesia and iron. The bacterial content ofthis product is relatively low, being lower than that of bulk fluid orfrozen egg white of the American market. As a consequence of theimproved methods of producing this product its stability is exceedinglyhigh. This product finds use as a general food base for all sorts ofculinary purposes in which its physithe red corpuscular matter fromanimal may be used with advantage.

While the different features of the inven tion have been described intheir preferred forms, it is to be understood that they may be embodiedin other forms within the scope of the following claim Having thusdescribed the invention, what is claimed is: l. A centrifuge forcompletely separating blood comprising a bowl, means for rotating thebowl at high speed, a delivery nozzle for introducing the blood streamto within the bowl, positioned so as to cause, during the operation ofthe centrifuge, the entering blood stream to initially impinge upon aslowly rotating wall of blood, the portion of the interior of thecentrifuge bowl within which. the blood is brought up to speed beingentirely devoid of obstructions, a plurality of vanes positioned in theupper portion of the bowl, and a tapered dam located centrally in theupper portion of the bowl and :ooperating with the vanes to accomplish acomplete separation of the inner and outer portions of the blood stream.

2. A centrifuge for completely separating the red corpuscular matterfrom animal blood zomprising a bowl, means for rotating the bowl at highspeed,-a delivery nozzle for introducing the blood stream to within thebowl positioned so as to cause, during the operation of the centrifuge,the entering )lood stream to initially impinge upon a slowly rotatingwall of blood, and a conical dam flaring outwardly from its lowerportion and located in the upper portion of the bowl for retardingmovement of the red corpuscles from the vicinity of the dischargeoutlets for the red corpuscular matter toward the central portion of thebowl.

3. A centrifuge for completely separating the red corpuscular matterfrom animal blood comprising a bowl, means for rotating the bowl at highspeed, a delivery nozzle for introducing the blood stream to within thebowl positioned so as to cause, during the operation of the centrifuge,the entering blood stream to initially impinge entirely upon a slowlyrotating wall of blood, and a dam in the upper portion of the bowlarranged to prevent the traverse of red corpuscles along the walls ofthe bowl and toward the interior of the bowl and shaped to form asecondary chamber within which any red corpuscles passing around the dammay accumulatewithout contaminating the clear separated portion of theblood.

4. A centrifuge for completely separating the red corpuscular matterfrom animal blood comprising a bowl having vanes located in the upperportion thereof for maintaining the material at the speed of the bowl,the vanes having central cutaway portions forming a central opening attheir upper end, and a ported and terminating in the. opening formed bythe central cutaway portions of the vanes.

5. A centrifuge of the class described comprising a bowl having asubstantially cylindrical inner surface entirely devoid of obstructionsthrough its lower half, means for rotating the bowl at high speed,adelivery nozzle for introducing liquid into the lower portion of thebowl, a plurality of radial vanes located in the upper portion of thebowl and having inwardly curved lower edges, and a tapered dampositioned centrally in the upper portion of the bowl at the upper e gesof the vanes and serving to complete the separation of the inner andouter liquid strata. 7 7

6. A centrifuge of the class described comprising a rotating bowl, meansfor introducing liquid atone end of the bowl, a plurality of vanesmounted within the bowl and removed from the entrance point of theliquid, the vanes at the inlet end having converging edges designed togradually bring up to the speed of thebowl and at opposite ends havingcentral cut-away portions to form a space adjacent the discharge end ofthe bowl, and means for withdrawing the two the liquid 9

